The invention relates generally to radio antennas. More particularly, the invention relates to terrestrial radio and satellite communication antennas for vehicles and other mobile or fixed structures. The invention also relates to an integral antenna assembly that comprises one or more antennas for mounting externally on the surface of a vehicle or other mobile or fixed structure.
With reference to FIGS. 1 and 2, a number of antenna systems have been proposed which provide for the reception of satellite transmission signals on vehicles and other mobile or fixed structures. FIG. 1 illustrates a known antenna system that allows transfer of RF energy across a dielectric such as glass for reception of satellite transmitted signals. The antenna illustrated in FIG. 1 provides for the transfer of radio frequency (RF) energy through glass or other dielectric surface to avoid having to drill holes, for example, through the windshield or window of an automobile for installation. After-market glass-mount antenna systems are advantageous because they obviate the necessity of having to provide a proper seal around an installation hole or other window opening in order to protect the interior of the vehicle and its occupants from exposure to external weather conditions.
In the known antenna system 20 depicted in FIG. 1, RF signals from an antenna 22 are conducted across a glass surface 24 via a coupling device 26 that typically employs capacitive coupling, slot coupling or aperture coupling. The portion of the coupling device 26 on the interior of the vehicle is connected to a matching circuit 28 which provides the RF signals to a low noise amplifier (LNA) 32 at the input of a receiver 34 via an RF or coaxial cable 30.
FIG. 2 illustrates an alternative embodiment of the antenna system of FIG. 1, except that antenna 42 has been displaced to the roof of the vehicle, and is kept in place by a magnet or other securing means. Through cable 54 the RF signal travels to coupler 45, through the vehicle""s glass (e.g., back windshield) and to second coupler 44. The RF signal then travels through RF cable 46A to LNA 47 and then through RF cable 46B to receiver 48.
Both types of antenna mounting systemsxe2x80x94the window mount system and roof mount magnetic system of FIGS. 1 and 2 respectivelyxe2x80x94suffer from serious deficiencies. First, the antenna of either FIG. 1 or FIG. 2 is, in all likelihood, a second or even third antenna, and thus adds an unsightly appearance to the vehicle or structure. Regarding the window mount system of FIG. 1, RF coupling loss through glass is generally 1 dB or higher. This causes an increase in noise figure that results in degradation of receiver sensitivity.
Regarding the body mount system of FIG. 2, there are also serious deficiencies. For example, the installation of antenna 42 is located remotely with respect to LNA 47 and radio receiver 48 is generally considered unattractive to consumers of mobile satellite services. This is true for several reasons. First, an antenna mounted on the roof of a vehicle adds to the clearance height of the vehicle, which may be prove to be troublesome if parking in a garage. Often, users will forget that the antenna is on the roof, and will cause damage either to the antenna itself and/or the vehicle. Or, the user may have to stop the vehicle, exit it, and dismantle the antenna in order to proceed to park in the garage. This is, of course, a needless waste of time and energy.
Secondly, the roof mounted antenna is unsightly, not only to the external observer, but also to the occupants in installations where the RF cables must be routed through the interior of the vehicle. In the case of a window mounted antenna, the couplers may obstruct vision and generally make the appearance of the vehicle unsightly.
A need therefore exists for a vehicle antenna mounting system whereby both types of antenna (i.e., a vehicle""s OEM supplied AM/FM antenna and an antenna for the reception of SDARS signals) can be co-located, so as to minimize, if not entirely prevent, any additional holes in a vehicle""s exterior shell or eliminate the need to locate a magnetically mounted antenna on the glass of an auto, or to use antenna couplers in the glass portion of an auto, yet provide an integral assembly for installation on the exterior of a vehicle, and an effective means for reception of both terrestrial AM/FM signals and satellite transmitted signals.
The above described disadvantages are overcome and a number of advantages are realized by the present invention which relates to a combined satellite and terrestrial antenna system for a structure. The combined satellite and antenna system comprises a terrestrial antenna mounted on a mounting assembly, and a satellite antenna concentrically mounted with respect to the terrestrial antenna, with the mounting assembly comprising a low noise amplifier circuit and a bezel, the bezel adapted to contain the low noise amplifier.
The present invention further relates to a combined satellite and terrestrial antenna system for a vehicle, which comprises a terrestrial antenna mounted on a mounting assembly, and a satellite antenna concentrically mounted with respect to the terrestrial antenna, with the mounting assembly comprising a low noise amplifier circuit and a bezel. The bezel is adapted to contain the low noise amplifier, and the mounting assembly is mounted on the vehicle.
Additionally, the present invention relates to a method for mounting a combined satellite and terrestrial antenna system on a structure comprising the steps of mounting a terrestrial antenna on a mounting assembly; mounting the satellite antenna concentrically with the terrestrial antenna; mounting the mounting assembly in a mounting hole on a structure, wherein the mounting assembly comprises a low noise amplifier circuit and a bezel, with the bezel adapted to contain the low noise amplifier; locating satellite receiver hardware in proximity to the combined satellite and terrestrial antenna system; and connecting the satellite antenna, the terrestrial antenna, the satellite receiver hardware and terrestrial receiver hardware with appropriate cables.